Sprayable and injectable visible-light Kappa-carrageenan hydrogel for in-situ soft tissue engineering.

The aim of this study was to develop injectable and sprayable visible-light crosslinked Kappa-carrageenan (κCA) hydrogel and to investigate the role of polymer concentration (2, 4 and 6 wt%) and degree of methacrylation (6 and 12%) on its properties. It was found that, the average pore sizes, water content and swelling ratio of hydrogel were tunable by changing the methacrylate κCA (KaMA) concentration and methacrylation degree. Furthermore, the mechanical properties of KaMA could be noticeably modulated, depending on the formulation of hydrogel. Tensile and comprehensive modules were enhanced from 68 to 357 kPa and from 213 to 357 kPa, respectively, by increasing KaMA concentration from 2 to 6 wt% and methacrylation degree from 6 to 12%. Furthermore, with increasing methacrylation degree and polymer content, the absorbed energy and energy loss were increased. Moreover, recovery significantly enhanced from 27.3% to 74.4% with increasing polymer content from 2 to 6 wt%. Finally, visible-light crosslinked KaMA hydrogels not only was biocompatible, but also could promote HaLa cell and fibloblasts function. The visible-light crosslinked KaMA is thought to be an exclusive biomaterial as a sprayable hydrogel being able to cover skin injuries or to inject as a bio-printing material to in situ heal soft tissue damages.